Radius and angle dressers for figuring the edges of grinding wheels to desired configurations have heretofore been capable of forming edge surfaces having a combination of rectilinear and single radius arcuate cross sections. Exemplary of such dressers are those disclosed in U.S. Pat. No. 1,994,386 issued to T. H. Dardani on Mar. 12, 1935, U.S. Pat. No. 2,343,949 issued to F. S. Bellinger on Mar. 15, 1944 and U.S. Pat. No. 2,336,758 issued to E. V. Statia Sr. on Dec. 14, 1943.
The prior art dressers, however, are incapable of generating tangent concave, convex and angled or double radius and angled grinding wheel edge surfaces without rezeroing and resetting the apparatus, which requires a precise and difficult repositioning of the cutting edge of a tool.
It is an object of the present invention to provide a novel method for radius and angle dressing to form the edge surface of a grinding wheel to various compound configurations with an initial setting of the radii to be generated.
It is also an object to provide such a method capable of forming tangent concave and convex grinding wheel edge surface configurations.
Another object is to provide such a method capable of forming double radius grinding wheel edge surface configurations.
It has been found that the foregoing and related abjects may be readily attained in a method of dressing a grinding wheel or the like to provide two different radii surfaces thereon, wherein a cutting tool having a cutting edge is mounted on a tool support member of a radius and angle dresser having a support member in which a first shaft is mounted for rotation and which in turn has a second rotatable shaft mounted at one end there of. The axes of rotation of the shafts are parallel, and the second shaft is selectively shiftable radially of the axis of rotation of the first shaft between positions lying in a first plane extending to opposite sides of the axis of rotation of the first shaft, while maintaining the axes of rotation parallel. The second shaft is oscillatable independently the first shaft, and first and second locking means are associated, respectively, with the first and second shafts and are operable to limit rotary oscillation of the shafts. The dresser is zeroed by rotationally centering said first and second shafts, and the cutting tool is positioned relative to the second shaft to position the cutting edge thereof at a selected elevation relative to the axis of rotation of the second shaft. The second shaft is radially shifted relative to the first shaft to position the cutting edge at a selected elevation relative to the axis of rotation of the first shaft. A grinding wheel or the like to be dressed is positioned adjacent to the cutting edge and the second shaft is locked against rotation relative to the first shaft. The first shaft is freed for a selected degree of rotational oscillation relative to the supporting member.
The first shaft is rotationally oscillated about its axis of rotation without affecting axial movement thereof to engage the cutting edge with the associated grinding wheel or the like to generate thereon a radius surface set with respect to the axis of rotation of the first shaft. The first shaft is locked at a selected rotational position along its path of oscillation relative to the support member. The second shaft is freed for a selected degree of rotational oscillation relative to the first shaft, rotationally oscillated about its axis of rotation without oscillating the first shaft to engage the cutting edge with the associated grinding wheel or the like to generate thereon a radius surface set with respect to the axis of rotation of the second shaft. The first and second radius surfaces are thus generated without intervening repositioning of the cutting tool relative to the shafts.
Preferably the second shaft is also radially shiftable relative to the first shaft between positions lying in a second plane disposed perpendicularly to the first mentioned plane and extending to opposite sides of the axis of rotation of the first shaft. The method then includes the step of shifting the second shaft back and forth a selected distance in the second plane without rotating the shafts so as to engage the cutting edge with the grinding wheel to generate an angled surface on the wheel. The first shaft is maintained at a selected degree of rotation away from its rotational zero position during the shifting of the second shaft. The second shaft is maintained at a selected radial distance along the second plane from the first shaft while the second shaft is rotationally oscillated.
Conveniently, handle means is provided on the other end of the first shaft and is operated to effect oscillation of the first shaft. Similarly, the second shaft has an end portion opposite that supporting the cutting tool and this end portion is operated to effect oscillation of the second shaft.
The locking means desirably includes stop means on the first shaft and on the support member, and the first shaft is oscillated until the stops abut .